This reminds me of a previous employer that mandated strictly 20% employees must be rated as underachievers and get a 0% COL adjustment i.e. a pay cut in the face of inflation. But, my whole team was important to our successful year. Yet, someone is forced to take the pay cut.
It's a system predicated on the false assumption that the bottom 20% by some arbitrary ranking aren't fulfilling their job duties nor instrumental to success. It exists to codify and justify whatever the employer desires, which was in this case and as often is the case--underpaying employees.
In my experiences, performance reviews are 5% facts and data, 35% writing skills, 60% company predetermination of your worth and compensation.